Question

i^51

Answer 1

You divide 51 by 4 and look at the remainder. 51/4 = 12 remainder 3
i = sqrt(-1)
i^2 = -1
i^3 = -sqrt(-1)
i^4 = 1

So since you have remainder 3 you choose the i^3 = -sqrt(-1)

Answer 2

so the answer is -i ???